The present invention relates to electronically steered phased array antennas and particularly to a control system for a phased array antenna that electronically performs both beam steering and beam-shaping operations.
Electronically scanned phased array antennas require a high throughput control system capable of steering the planar wavefront. Three general types of control systems for performing beam steering operations on phased array antennas have been described by T.P. Waldron, S.K. Chin and R.J. Naster in their article, Distributed Beamsteering Control of Phased Array Radars, Microwave Journal, pp. 133-146, Sept. 1986.
The first type is a centralized array control system in which a central beam steering computer generates a serial stream of phase commands for each of N rows or columns. The second type involves the central generation of M row and N column phases, which are added at each element in the array. The third type is an element level control computed from broadcast phase gradients by a microprocessor or by a custom controller. This third type of beam steering control system is recognized as providing: maximum steering throughput, reduced bus bandwidth requirements, and simplified error compensation at the element level.
However, all of these prior art general types of beam steering control systems have two disadvantages. Each of them is relatively slow in electronic steering throughput because none of them fully exploits the parallelism of the phase shift computation at the element level. In addition, none of these three types possesses the capability of forming any arbitrary beam shape as a function of phase at the sample points on the phased array.